Let Go
by Revhead
Summary: Dean does what he set out to do. But when it is finished, he has trouble letting go. Can Castiel get through to him, or is the Mark too strong? A season 9, Mark of Cain fic. UPDATE: The final chapter "Sunset" has now been posted.
1. Chapter 1: Let Go

**Let Go**

When Castiel finally found him, he feared he was already too late.

The man stood alone in a wasteland of death and destruction. The ground was strewn with bodies that had been hacked and slashed apart. The earth was stained red with the blood of the slain.

No demon had survived the massacre. Every last one of them had perished in one man's war against Hell. Even Abbadon lay dead at his feet.

It was over, then. Hell wasn't closed, it was empty. The world was that little bit safer. They had victory at last.

But at what cost?

Each of those demons had been possessing an innocent human. When they died, their vessels died also. How many fathers, mothers, brothers, children, had lost their lives here today?

Many of the souls in Hell had not yet mutated into monsters. But they had been purged with the rest.

Every war had casualties, Castiel knew. Collateral damage was unfortunate, but unavoidable. He grieved for those who had perished, but believed they were going on to a better place.

His true concern was for Dean.

The last man standing on Hell's final battlefield, he looked more lost and alone than Castiel had ever seen him.

Nothing left to fight, nothing left to kill.

Everything had been building up to this moment, and now there was nothing.

All he had was a Blade in his hand, and a Mark branded into his skin.

He was covered in blood that was not his own, and he was shaking.

Castiel approached cautiously.

"Dean."

Dead eyes stared sightlessly past him.

Black eyes.

"Dean."

The shaking stopped. One by one, every muscle in Dean's body tensed with anticipation. Every fibre of his being exuded the raw, unadulterated power of a man born and trained and unafraid to kill.

Black eyes fixed on the intruder, and a feral grin began to curve his lips.

The Mark glowed.

"I am not here to fight you, Dean."

A flicker of uncertainty.

This close, Castiel could see the white-knuckled grip Dean had on the handle of his weapon. Every moment of contact was pumping poison into his veins.

"I'm here to help you."

Dean stared at him without recognition or comprehension. He was already so far gone.

Castiel wondered if Dean even knew his own name.

"Dean… If you had only talked to me sooner, I could have told you about Cain and the deal he made with Lucifer. I could have warned you about the Mark and what it would do to you. I could have stopped you before you ever laid a hand on the First Blade. I could have prevented this."

But that was exactly why Dean _hadn't_ told him. He held no value for his own life unless he was using it to save other people. Hunting wasn't just a job for him, it was his life. His purpose. He would sacrifice everything for the cause. He would even forfeit his own soul.

He thought everything was his responsibility. He believed he was the one who had to fix it all.

Even if Castiel had been given the chance to warn him, Dean wouldn't have listened.

He would have said killing Abbadon was worth it.

But seeing Dean now, so far from the man who had laughed at an angel in a brothel, Castiel felt that the cost was too high.

They were losing Dean. They were losing the man who loved pie, the man who sang off key, the man who treated his car like a beloved child, the man who held onto hope when there was none, the man who pushed through the pain, the man who never gave up on family, the man who always strove to do what was right, the man who did everything out of love. The Righteous Man with the most beautiful soul Castiel had ever seen.

The Mark was corrupting him. Polluting his goodness, burning away everything that made him who he was. Leaving nothing but a killer in his place.

"Dean? Tell me there is still some part of you in there. Tell me I am not too late."

Dean did not answer, but he had not made an attempt to kill Cas either. If he were truly lost, there would be no differentiating between friend and foe. He would not have stopped when the demons were dead. He would have gone on to find more flesh to sink his blade into.

Castiel chose to have hope.

"Listen to me very carefully, Dean. You need to let go of the First Blade."

Dean took a hasty step back, the blade coming up defensively.

"I am not going to hurt you," Castiel soothed. "Just let the blade go, just for a moment. Prove to yourself that you can."

Dean looked down at the jagged bone clutched so tightly in his hand. "Mine. Birthright."

The Winchester brothers, descended from the bloodline of Cain and Abel. To suit their own purposes, the angels believed it was Dean's destiny to become Michael's vessel and kill Lucifer. But maybe every road in Dean's life led _here._ Maybe he was always going to follow in Cain's footsteps.

Castiel knew where this path would take him.

Killing one's own brother. Castiel would never believe Dean was capable of killing Sam, but, in light of Sam's death wish, all of a sudden it became an alarming possibility. If Dean did it, if he sent Sam's soul to Heaven – to the eternal peace Sam was ready to embrace – the transformation would be complete. Dean would be a full-blooded demon. He would be a Knight of Hell, the first of a new order. He would raise a new generation of demon, and in a few millennia demons would once again terrorise the Earth.

"The Blade has served its purpose, Dean. You killed Abbadon, you destroyed the demons, and you vanquished Hell. Your job here is done. You can let go now."

Dean's gaze fell on the Knight lying dead at his feet. "I… killed the bitch."

"Yes, you did. It's over, Dean."

Dean shook his head. "I need… I need…"

"That is the Blade talking. Its thirst for blood will never be sated, no matter how many you kill. You need to put it down. Trust me, those urges will fade. Just let go."

Dean looked at the Blade, then turned helpless eyes on the angel. "I can't."

"Then let me help you."

Dean wavered.

Castiel took a step forward.

Dean went from docile to hostile in an instant, his Blade slashing towards the angel with deadly intent.

Supernatural reflexes saved his life. He vanished from the physical plane, allowing the blade to pass through where he had been standing a split-second before, then reappeared a moment later. Before the hunter could come around for a second attack, Castiel caught Dean's wrists.

"Stop! You don't want to do this Dean. You don't want to hurt me."

Dean struggled in his grip, but Castiel held firm.

"Let go, Dean. Drop the Blade before you do something you will regret."

Dean snarled, gnashing his teeth at him, bucking and kicking and twisting for all he was worth. Castiel drew on every ounce of strength and Grace he had to hold the almost-demon at bay.

"Calm down, Dean. I am not the one hurting you. It is the First Blade. It is poisoning you. You _have_ to let it go!"

"No!"

Dean jerked one hand free and slammed a fist into Castiel's jaw. Cas recoiled but didn't dare release the wrist he now held in a death grip. If Dean regained use of his right arm, Castiel would be dead before he hit the ground.

"Dean-"

The fist flew again, cracking violently across his nose. Blood spurted everywhere. Dean punched him again. And again.

But Castiel wouldn't let go.

"Fight it, Dean! I know you can fight it! You are stronger than this!"

He could feel skin splitting, bones crunching, internal blood vessels bursting, but he would not relent. Not for his own sake. Castiel did not fear death. He feared what his death would do to Dean when he came back to himself. If he ever came back to himself.

He thought about Cain, and what it had taken to convince the Father of Murder to put down his Blade.

Collette.

How had Cain phrased it? _She loved me unconditionally._

And if loving Dean when he was covered in blood, when his eyes were black, when he was trying to beat Castiel to death with his bare hands wasn't unconditional love, nothing was.

But for Dean Winchester, one word was even more powerful than love. Love was frightening, taboo, weakness. Feelings of love were never admitted out loud. But Dean's first priority, his primary motivator, the most important thing in his life was-

"Family, Dean. You said that we were _family_."

Dean froze.

Stared at him, wide-eyed, as though seeing him properly for the first time.

"C-Cas?"

"It is me, Dean. I'm right here."

"Cas?"

"I'm here, Dean. I'm here, and I'm not going anywhere. I promise."

Dean began to tremble. "C-Cas- I didn't- I couldn't-"

Guessing the cause of Dean's distress, Castiel drew on his Grace to heal his injuries. "I am fine, Dean. But I am worried about _you._"

"I-"

"You're not okay, Dean. You need to let go of the Blade."

Dean's eyes fixed on the weapon in his hand. A look of intense concentration spread across his face. His entire arm shook. One finger peeled away-

"I can't!" he gasped, reflexively tightening his grip on the blade as though it was a lifeline. "I can't. I'm not strong enough."

Castiel had heard those words before. "Yes you are, Dean," he said quietly. "I believe in you. You can do this. You can let it go."

He tried again, straining to release the blade. But, as if in retaliation, the Mark on his arm burned an angry red, and he sagged in Castiel's grip. "No," he panted. "I can't. I need it. It is a part of me now."

"This Blade is keeping you away from your family, Dean! You know you can't go anywhere near Sam with that bloodlust pumping through your veins. You hurt me. You'll hurt him. You'll hurt innocent people, and I know you don't want that. You _have_ to let go!"

"But-"

"_Drop it, _Dean!"

Dean gasped, his hand springing open of its own accord. The Blade fell to the ground with a dull thud.

Without hesitation Castiel snatched up the cursed weapon and vanished with it, taking it back where it belonged – the bottom of the deepest ocean. He made sure it was buried deep, and then dumped two hundred tonnes of rock on top of it to be certain.

When he returned, Dean was in a crumpled heap on the ground, sobbing hoarsely.

Castiel's heart wrenched. He knelt down beside his hunter and gently tilted his chin up. "Dean…"

The eyes that looked up at him were no longer the soulless black of a demon. They were green, but awash with tears. "Cas? You- you came back?"

Castiel smiled a little. He had finally learned the human custom for emotional reunions – he wrapped his arms around Dean and pulled him in close, embracing him tightly.

He whispered a single word in Dean's ear. "Always."

ooOOoo

_A/N: There it is, folks. Cas saves Dean, just like he always has and always will. I am considering continuing this with Cas helping Dean through withdrawal… thoughts? Thanks for reading, I hope you enjoyed! Remember reviews are love :)_


	2. Chapter 2: Come Clean

**Chapter 2: Come Clean**

"We should get you home," Castiel said quietly.

Dean gave a weary nod against his shoulder, but made no move to pull away from the angel's embrace.

The close proximity was strange for Cas, who had been on the receiving end of a few hugs but had never initiated one before now, but he was discovering that it was not at all unwelcome or uncomfortable. There was something about having Dean resting against his chest with his head tucked into Castiel's neck and a hand fisted in his coat that made Cas feel he finally understood the concept of sheltering someone under his wings. This was the man he had been trying to protect for years and here, in this moment, Dean was safe. As long as he was cradled within Castiel's arms, nothing could hurt him, not even himself.

He was surprised that the hunter had permitted it to last for so long, but he wasn't complaining.

Cas suspected this was something Dean sorely needed. He wondered how long it had been since someone had hugged Dean, really hugged him, in a way that said _it is going to be okay_ and _don't worry, I've got you_ and _I care_. He wondered how long it had been since Sam hugged him like that.

Too long, judging by the way Dean was clinging to him, as though he was afraid to let go.

Cas held Dean for as long as he needed. There was no rush, no hurry. He let Dean have this sanctuary, hidden and protected from the world until he was ready to face it again.

Somehow, it eased the ache in Castiel's heart, too.

But they couldn't stay here forever, kneeling in a field of blood. People had died here and the human authorities had no way of knowing the victims of Dean's one-man massacre had been possessed by demons. They needed to leave.

"Come on, Dean."

He didn't let go of his charge; contact was all that was necessary, whatever form it took. He simply spread his wings and transported both of them back to the bunker as they were.

But when Dean noticed the change in their surroundings he jerked away.

"Dean-"

"Where's Sam?"

The moment had clearly passed. Cas was saddened, but he didn't let it show. "Following a lead on Gadreel. He- wanted me to go after you."

It wasn't the whole truth. Castiel had seen Sam out hunting Gadreel on his own and asked where Dean was. Sam had responded by saying they were both doing what they had to. Castiel had been the one to make the decision to go after Dean, and Sam had chosen not to go with him.

Castiel understood his reasons. Sam had always been prepared to do whatever it took to save the world, and he just wanted this all to be over once and for all. If one or both of the Winchesters died in the struggle, then so be it.

But Castiel couldn't agree with him. Especially when it was not Dean's life at stake, it was his humanity. Cas had pulled him from the Pit once and after everything they had been through together he couldn't bear to lose Dean's soul to the darkness again.

"Sam's not here?"

Castiel shook his head.

"Good. He shouldn't see me like-" Dean gestured vaguely, rolling his shoulders as if he wished he could shed the grime with that single motion. "I'm going to hit the shower." He hesitated before walking away. "Will you-?"

"I'll be here," Cas promised.

ooOOoo

Dean stood under the spray of steaming water, eyes closed so he wouldn't have to see the diluted blood sliding down his body and swirling down the drain.

None of it was his.

The battle, if it could be called that, had lasted two days. He had slaughtered every last demon on the face of the Earth and in the hellfire beneath it, and none of them, not _one_, had managed to lay so much as a scratch on him.

He knew he was a damn good hunter, but he wasn't that good. No one was that good, no human anyway.

He didn't know _what_ he was anymore.

The Mark on his arm burned, as though to remind him.

One thing was abundantly clear. He was a killer.

Every second of the battle was permanently etched in his memory. He had sliced and diced and stabbed and carved and slashed and cut his way through hundreds of demons. He hasn't cared that each one was possessing some poor innocent bastard who probably had no idea demons existed until one shoved its way down their throat. He hadn't bothered to exorcise any of them, and if any tried to smoke out he made sure he stabbed their meat suit through the heart before they could.

Some of them had been possessing _children_. One little boy had looked just like Ben.

Dean never even hesitated.

Hell, he _enjoyed_ it. He tasted the blood of his victims and he _liked_ it. He craved it.

Even now, with revulsion roiling in his gut as he relived what he had done in vivid techni-colour detail, part of him still craved the sweet taste of violence and death. The Mark still burned. His hand still clenched and unclenched around a blade that was no longer there.

He _hungered._

Dean lashed out blindly, snatching up a scrubbing brush and gripping it with all the ferocity he would the First Blade. This was his weapon now.

The water was hot enough to scald him, but it couldn't wash away the stain on his soul. It couldn't remove the blood from his hands.

But maybe he could scrub himself clean, or die trying.

The first swipe of rough bristles across his skin brought an instant of relief. He pressed harder, scraping the brush over tender flesh, savouring the screech of abused nerve endings. He needed to feel pain to forget the pain he had inflicted. Back and forth, harsher and deeper, Dean tried to scrub all the way down to his soul. He scrubbed and scrubbed at the blood, but it wouldn't come off, it wouldn't wash away, it just kept coming, spilling over his hands and arms and chest, never ending, the inexhaustible blood of hundreds.

Enraged, he threw away the brush and clawed at the stains with his nails, trying to strip the taint of evil from his body.

But the blood kept flowing and it felt good, it felt right, because he lived to spill life blood, he lived to bring death. He would kill anything, anyone, even himself.

He scrambled out of the shower, ripping through cupboards until he found a blade. Not the one he had lost, not the one that had been stolen from him, but a razor that in the hands of a killer could do the job just as well.

And the two parts of him, the demon and the man, were in agreement because one wanted to kill and the other wanted to die.

He was a monster. He needed to be hunted, but any hunter who came after him would die bloody. He was the only one strong enough to take down himself.

He had to do it now, before his resolve weakened. He didn't want to hurt anyone else.

ooOOoo

Castiel hesitated outside the bathroom door. Dean had lectured him about privacy more than once, so he knew now that walking in on someone while they were in the shower was not socially acceptable. However, he had started second-guessing the wisdom of letting Dean out of his sight half an hour ago and was edging closer and closer to full-blown panic by the minute. Dean shouldn't be taking this long.

He knocked on the wooden panel with his knuckles, hoping the sound would be heard over the running water. "Dean?"

No reply.

He called out louder.

Nothing.

"Dean, if you do not answer me I am coming in whether you are clothed or not."

Two more seconds of waiting, and then Castiel decided embarrassment was a small price to pay for Dean's safety and passed straight through the door.

The sight that greeted him was horrific beyond words.

Dean was covered in blood. _His _blood. His skin was in tatters, scrubbed and scraped raw, bleeding profusely all over the tiled floor.

But worse, so much worse, was seeing the way Dean stood in front of the mirror, ostensibly calm and collected but poised to _stab himself in the heart_.

Cas lurched forward. "Dean, _no-_!"

He was too late. The broken razor blade plunged deep into Dean's chest.

A devastated cry escaped Castiel's lips, even as he moved on instinct to catch Dean's lifeless body when it crumpled.

But Dean didn't fall. He didn't even flinch.

"D- Dean?" Disbelieving, Cas grabbed his shoulders and spun him around to view the damage. The hunter's aim had deadly accuracy; the blade had pierced his heart. But… he wasn't dead.

"Dean, what-?"

"That was my fourth try," Dean said dully. He yanked the blade back out, examining the wound that should have killed him with clinical detachment. "It didn't work."

"Good!" Cas exclaimed. If he didn't know that his Father had nothing to do with it he would have thanked God for Dean's survival. Words could not describe the terror that had struck him in the moment when he thought Dean was dead. "What were you _thinking_, Dean? How could you do something like that?"

Dean twirled the blade idly in his fingers. His reply was flat. "I was doing my job."

Only a Winchester. Only a Winchester would believe committing suicide was his _job._

Furious, Castiel snatched the razor blade out of Dean's hand and vaporised it with an intense flash of his Grace. "You were trying to kill yourself!"

Dean did not look cowed, or even apologetic. "And it didn't work. Which proves that I was right. I _am_ a monster.

"Dean-"

"And not just your garden-variety monster of the week, either. I'm the new Cain. I'm a friggin' _Knight of Hell_, Cas."

That was what Castiel had been afraid of, but if Dean was freaking out Cas needed to stay calm. "I think you are overreacting." After all, Dean hadn't taken the final step. And Castiel was confident he never would; Dean's instinct to protect his younger brother was too strong. He would never kill Sam, so his transformation would never be complete.

Dean was right, though. Even the partial metamorphosis had changed him dramatically.

"Oh sure. I just found out that the Mark on my arm has turned me into a demon, but everything is just _peachy_."

"Okay, so it is not ideal," Castiel conceded, "but it is not worth dying over. We will figure this out."

"There is nothing _to_ figure out. I was a hunter, I made a decision without thinking about the consequences, and now I am a thing that needs to die. That is all there is to it. So give me back my Blade and let me end this."

"No."

"Dammit, Cas-"

"_No,_ Dean. I could no more stand back and watch you kill yourself than you could let your brother die."

"When it is a choice between eternal life as a _demon _and deathI'd choose death."

"Well I am sorry, Dean, but I'd rather have you."

"You lost me from the moment Cain gave me his mark, Cas. I'm not the guy you knew. I'm dangerous. I'm _evil, _and I need to be stopped."

"You _did_ stop, Dean. You destroyed the demons and you didn't go any further. You let the Blade go. Those are not the actions of an evil creature, Dean, they are the actions of a man. A good man."

"If you hadn't turned up when you did…"

"That is irrelevant." 

"No it's not. What are you going to do, keep an eye on me for the rest of forever to make sure I don't go dark side?"

"Gladly."

"You're kidding me. You can't do that, Cas."

"I think you will find that I can. I am an angel, Dean. Eternal life is part of the package deal."

"And you want to spend eternity as a parole officer for a ticking demon bomb?"

"I want to spend eternity with _you._"

Dean stopped.

Dean stared at him.

Dean's lips parted to say something, but no words came out.

When it became clear that Dean had been shocked speechless, Castiel took it upon himself to fill the silence. "Life as an angel is lonely," he explained. "Up there, family doesn't mean the same as it does here. You are surrounded by your brothers and sisters, but because emotions are discouraged there are no personal bonds. No romance, or friendship, or relationships of any kind.

"Before I met you, Dean, I didn't know that there was anything more to life than what we had in Heaven. But you taught me how to feel. How to care. How to love. You were my first friend, and when it comes right down to it, you are all I have. Our relationship means everything to me, Dean.

"But you were human. Even if you lived to old age, your life would only ever be a tiny fraction of mine. For years I have been trying to come to terms with the fact that someday I was going to lose you and I was going to be alone again. Forever. Do you have any idea how that felt? How terrified I was?"

"I couldn't imagine anything worse," Dean whispered.

"Exactly." Loneliness was one thing that Dean Winchester understood all too well. "But now there is a chance that you will live. I'm sorry Dean but I am not going to let that go. I am not going to let _you_ go."

"But… if I hulk out…"

"I won't let that happen," Cas promised. "You keep me human, Dean, you always have. Now it is time for me to return the favour."

"I don't know…"

"Trust me, Dean. Can you do that?"

He hesitated. "I think so."

"Then believe me when I say that everything is going to be alright."

Dean did not look entirely convinced, but he didn't argue, which meant he was willing to try. "You really… uh, think that I might be okay?"

"I do."

Dean took a few moments to absorb that declaration.

Then a small smile curved his lips. "Dude… you just professed your undying love to me while I am standing naked in a bathroom."

Castiel rolled his eyes. "You humans and your bizarre concepts of body consciousness. I have seen your soul laid bare, Dean. Seeing you unclothed is hardly earth-shattering. "

Dean flushed.

"However, it distresses me to see the harm you have inflicted upon yourself." Maybe Dean couldn't die, but his body was not self-repairing like an angel's was. Cas reached out, gently cupping Dean's chin and letting his Grace flow through to heal his injuries. "Don't ever do that again," he chided. "You scared me."

Dean's gaze dropped shamefully to the floor, but when he found the courage to meet Castiel's eyes he found only caring and concern in their depths. He took in a steadying breath. "Sorry, Cas."

"Forgiven." Castiel smirked a little. "Now put some clothes on before you catch a cold."

ooOOoo

_A/N: Wow, an entire chapter written in one day. You lovely reviewers inspired me. Who knows, there may be more of this story to follow…_


	3. Chapter 3: Changes

**Changes**

Castiel wanted to believe the worst had passed.

The First Blade was gone, Dean's eyes were not black, he was not drenched in blood and in the past 24 hours he had made no further suicide attempts. It was progress, of sorts.

With the Mark of Cain hidden from view beneath Dean's leather jacket, Castiel could almost believe that it was a normal day.

Not being human himself, it took Castiel a while to realise just how out of the ordinary things really were. He caught on, though, when he noticed that Dean had been staring into the open fridge for ten minutes without moving. Such behaviour was strange in and of itself, but when Cas took into account the fact that there was leftover apple pie in said fridge, it became downright alarming.

"Dean?"

"I'm not hungry," Dean said.

Cas frowned a little. "Okay… well, the pie will still be there later. No one is going to eat it if you leave it until you do feel hungry, don't worry."

Dean sighed, pushing the fridge door closed. "You don't get it. I'm _not hungry_."

"When was the last time you ate?"

"I don't remember. Four days ago? Five?"

It had been an intense few days, and it was not uncommon for food to be forgotten by the wayside during such times, dropping low on the list of priorities as more urgent matters demanded attention. But if Castiel recalled correctly, hunger pangs typically occurred every few hours for a human, and the longer they went without food the hungrier they became. Dean should be ravenous by now. Besides, Dean was _always_ hungry.

But then he remembered that, while humans did indeed require food to sustain them, demons did not.

"Oh."

Dean huffed a mirthless laugh. "Yeah. I'm never going to be hungry again. Isn't it just fan-friggin-tastic?"

Castiel knew better than to take his words at face value. Dean looked anything but pleased by this turn of events. "That was sarcasm."

"No, Cas, I am _overjoyed_ to be free from burgers and bacon and peanut m'n'ms and liquorice and pie. Oh and hey, just as awesome, apparently I don't need to sleep anymore. I get to stay up all night _every_ night forever. So much time to _think_. This Mark is the best thing that has ever happened to me."

It was definitely sarcasm. Castiel knew well the spiral of self-hate and loathing that a person could be sucked into when they had too much time alone with their thoughts.

"Hell, I don't even need oxygen anymore. Alcohol is friggin' useless now, too, by the way."

Privately, Castiel thought that had less to do with the Mark and more to do with Dean building up an immunity to the effects of alcoholic beverages. Sobriety and intoxication were worn the same by the hunter who had sunk to the bottom of a bottle years ago and never tried to claw his way back out.

"You just have to look for the positives in this, Dean. No more grocery bills, no more nightmares. You will never grow old, wrinkled or frail."

"Never thought I would anyway," Dean muttered. "I thought I was going to die young. I thought- I thought this whole deal with the Mark would be the death of me. I wanted it to be."

"Dean…"

"I was always meant to be the one who died first. The heart attack should have killed me. I should have died in the car crash. I should have rotted in Hell. The universe has tried to gank me so many friggin' times, and I never cared because at least it meant I would die before Sammy. He can live without me, I know that. But I can't live without him. Except I don't have a choice, because the universe has given up on trying to kill me and has decided to make me _immortal_ instead. There are no if, buts, or maybes, no ways around it; I am going to watch my brother die while I just keep going and going.

"That is my _worst_ nightmare, Cas, and now it is my reality so don't try and tell me that there is a _positive_ side to all of this."

Castiel stared levelly at him, pushing aside any feelings of hurt. Eternal life was a lot to adjust to, and for a man who loved his brother as much as Sam did Cas was sure a damaged angel was a poor consolation prize. But just as Dean was apparently determined to be miserable, Cas was determined to help him learn to appreciate life again.

"You want your brother to die old and happy, don't you Dean?"

"That is all I have ever wanted."

"If you had died young, you would never have seen Sam's future. Now you can. You can be Sam's best man at his wedding and see him settle down into a normal life. His kids will be able to say they have the coolest uncle in the world. You will have the chance to meet his grandchildren. You can protect him and his family through the generations. You can be there for your brother until he is old and grey and his rightful time has come. And then you can know that you did it, Dean, you looked after your baby brother and made sure he lived a full, rich life. Isn't that a future worth sticking around for?"

"I… never thought about it like that. I can see Sammy have his happy ending. And then I'll be-"

"Free?" Castiel suggested. "The burden of responsibility that you have borne since you were a child will be lifted, and you will bear no guilt; rather, you will be able to congratulate yourself on a job well done. And then you will be able to live for _you._ Find out what _your_ happily ever after is."

"I don't really know how to do that," Dean confessed.

"Me neither," Cas said. Free will was still a concept he was getting used to. "But we can work it out together."

Dean smiled. A real, genuine smile. "I'd like that."

"Besides," Cas added as an afterthought. "Hungry or not, there is no rule saying you can't eat pie."

Dean's grin broadened.

ooOOoo

_A/N: Okay, so that was an ultra-short chapter. But sweet, I hope :) I think, if there is another chapter to come, we will see that Dean is not out of the woods yet, and Sam may finally return to the bunker…_


	4. Chapter 4: Progression

**Chapter Four: Progression**

"You're wasting your time," Sam said.

He was sitting in an abandoned warehouse, tied to a chair, watching as his prey-turned-predator paced restlessly back and forth.

"I'm telling you, he's not coming," Sam persisted. He was sick and tired of being used as bait; he wished the psycho angel would just kill him or let him go already. Unfortunately, Gadreel didn't seem inclined to believe Sam when he said this was a pointless exercise.

"He will come."

It was like talking to a brick wall. Except a brick wall would be more expressive, and probably a better listener too. "It has been three days! Don't you think if he was going to turn up he would be here by now?"

"You are his brother. He will not leave you here."

Sam rolled his eyes. "Just because we are related by blood does not mean that everything is picture perfect between us. It's the opposite, actually. Besides, after what I said to him the last time he 'saved my life' I doubt he will make that mistake again."

Gadreel stopped his pacing and turned to look at him. "You are not truly naïve enough to believe that mere words could dissuade your brother from saving you."

Sam didn't know. In the spirit of honesty – or, rather, in an attempt to make Dean feel the same pain in this existence that Sam felt every single day as he went through the motions of living a life he should have surrendered long ago – Sam had hit him where he knew it would hurt. If Dean's reaction to that conversation was anything to go by, he had taken Sam's words to heart. Sam had essentially said he would let Dean die, so it stood to reason that Dean would return the favour.

"Dean has more important things to do than come chasing after me. He knows that the job comes first."

Gadreel tilted his head slightly, giving Sam the all-seeing angel-stare that never failed to creep him out. "For all that you have grown up with him, you do not seem to know your brother very well," he observed. "You have been, and you always will be, Dean Winchester's first priority. He will do anything for you, give _up_ anything for you. You, Sam, are the only thing he cares about."

"Yeah, and that has gotten us both into more trouble than it is worth."

"You are referring to my possession of your body."

Sam gritted his teeth. "Among other things."

If anything, Gadreel looked sad. "His intention was not to harm you, Sam. He had no way of knowing that I was not who I claimed to be."

"I don't blame Dean for your betrayal," Sam snapped. "Or for Kevin." If he had not been so tightly bound to the chair, he would have punched Gadreel across the jaw – and then stabbed him to death. He deserved nothing less for what he had done. As it was, Sam's fury bubbled just beneath the surface, biding its time, waiting for the opportunity to strike. "But we were supposed to be 'Team Free Will' and Dean _stole_ mine when he made a choice for me."

"You said yes," Gadreel pointed out.

"Well I didn't know what I was agreeing to! I was ready to die and Dean didn't let me. He had _no right._"

"But you made the decision to live. I heard you. You may not have known what the deal for your survival entailed, but you cannot deny that you chose life over death. That was you, not your brother."

Sam shook his head. "No, I wanted out. I wanted peace. I wanted an end to all of this. Dean _stopped_ me."

"Tell me, Sam Winchester. If you saw a man standing out on a ledge, preparing to jump, and you had the chance to stop him what would you do? Would you let him commit suicide, or would you try to talk him down? Would you let him give up on life without a fight, or would you try to give him a reason to live?"

Sam frowned, disturbed by the question. "I don't… it would be his choice. It's none of my business."

"What if it was someone you knew? Someone you cared about? Someone like Amelia, or Jessica, perhaps? Would you be able to stand by and do nothing while they tried to end their own life? Or would you do anything in your power to save them?"

Sam glared, but his silence was apparently answer enough.

"So you see, Dean's actions were not as selfish or malicious as you believe. He was only looking out for you, as he has ever done."

Sam struggled to hold onto his anger, but unfortunately he could see the situation from his brother's point of view now. It didn't make what he had done right, and it didn't excuse the fact that he had rented Sam out as an angel condom without his consent, but Dean probably couldn't comprehend the horror of possession having never experienced it himself. He didn't know it was the equivalent, or worse, of letting his brother be date-raped. He thought he was saving him.

"I have been in your head, and I have seen how Dean has always tried to protect you," Gadreel continued. "It is who he is, and he will not change. That is why I know he will come to rescue you."

"If he does you are going to kill us."

"I have my orders," Gadreel acknowledged. "But do not worry; I will give you the opportunity to reconcile first. And I will kill you quickly."

"_No one is killing my brother,_" a voice growled.

Sam would recognise that voice anywhere. He _had_ come after all. Sam never should have doubted.

"_Dean."_

Dean stalked out of the shadows, his eyes fixed on the angel. There was a deadly fury written across his features, menace in his every step and lethal intent in his unwavering gaze. But he was in total control, moving with the lithe grace of a predator. Every atom of his being was committed to the hunt. The air around him almost seemed to crackle with a dread power.

He wasn't even holding a weapon, but there was no question in Sam's mind that Dean was there to kill.

Gadreel stepped forward, heedless of the danger. "I knew you would come, Dean Winchester."

"Sam hadn't been home in a few days. It wasn't hard to put two and two together."

"It's a trap, Dean," Sam warned. He shrank back a little under the withering look Dean gave him, realising that his brother had known exactly what he was walking into. He just didn't care.

"I am sorry it has come to this," Gadreel said. He sounded genuinely remorseful, even as his angel sword dropped from his sleeve into his hand. "I would prefer not to kill you."

A sneer curled the corner of Dean's mouth. "Don't worry. You won't."

"I'm sorry, Dean, but we both know how this will end. I am an angel. You are just a man."

"You think so? Why don't you try to use some of your angel mojo on me, then?"

Gadreel made a curt hand gesture that should have flung Dean across the room, but he remained rooted to the spot. The angel frowned, suddenly looking uncertain.

Dean pulled a can of spray-paint from his pocket, tossing it at Gadreel's feet. "Cas and I, we did a little re-decorating before I came in here. I saw what the warding did to you when I was trying to keep other angels out of Sam's hospital room. Same principle applies."

"You have weakened me, but I am not powerless."

"Of course. What chance does a mere _human_ stand against you?"

Warning bells started going off in Sam's head. "Dean…"

But it was as if Sam was invisible. Inconsequential. It all came down to the angel and the unarmed hunter, circling each other in the dance of death.

On an unspoken cue, they launched into battle.

Sam had been watching his brother fight his entire life, and he had _never_ seen Dean fight like this.

He wasn't a hunter.

He was the incarnation of violence.

It was effortless, the way he traded blows with the angel, as though he knew every move Gadreel was going to make before he made it and it was simply a matter of slipping into the right position to block his attacks. Dean never moved more than he had to, weaving through the angel's defences and striking with precision. His speed and strength were _impossible_. It looked to be a furious melee, but Dean was not even working up a sweat.

Gadreel was beginning to look nervous, but he didn't flee. Sam recalled the angel warding on the building, and realised that Gadreel probably _couldn't_ flee. Whatever the outcome, this would be the end. But at the rate things were going, it would be the angel who died here today.

As though he had come to the same conclusion, Gadreel abruptly broke off from the fight and lunged toward Sam.

Sam jerked back, but he was bound, helpless, watching with wide eyes as the sword bore down on him.

Dean grabbed Gadreel's arm and the angel _twisted_, turning the weapon on Dean faster than was humanly possible.

Momentum dragged Dean forward.

The sword ran Dean through.

"_No!" _Sam screamed. "_No!_ Not Dean, not my brother, you _bastard!_" He struggled more fiercely than ever against his restraints, trying to reach Dean before he bled out on the floor. He couldn't die yet, he _couldn't_-

Dean looked down at the blade protruding from his gut.

Casually, he pulled it out, flipped it in his palm, and stabbed it straight through Gadreel's neck.

The angel didn't even have time to gasp in shock. A blinding burst of light exploded from his vessel and when Sam uncovered his eyes, Gadreel lay dead, the ashes of his wings burned into the ground.

Dean was still standing.

In fact, he just stood there, staring down at the body. His right hand clenched and unclenched at his side, but other than that he was still. Frighteningly still.

Almost like he had been when he was holding the First Blade.

"Dean?"

Dean's eyes flashed up to look at him and for a moment Sam could have sworn they were black.

A whirlwind of thoughts and information and deductions swirled through Sam's mind as he pieced together the facts of Cain and the Mark and the Blade and his _brother._

"Oh my god. Oh my god, Dean, you're a-"

"Demon," Dean filled in, shaken out of his trance by the sound of his brother's voice. "Yes. 'Course you would figure it out faster than I did. You always were the smart one."

"_Dean_-"

Dean wouldn't look at him. To avoid meeting Sam's gaze, he examined the jagged tear in his shirt with faked interest. The fabric was crusted with blood, but the injury that should have killed him didn't even appear to cause him any discomfort. "I didn't read the warning label. On the bright side, though, I ganked all the demons."

"_All_ of them?" Sam gasped.

"Yep. There's only one Knight of Hell left. Me."

Sam was reeling, unable to come to terms with what he had seen or what Dean was telling him. He could only stare at his brother in horror.

Dean sighed. "I know, Sam. You don't have to say anything. I'm a monster, I get it."

A monster? A demon? A soulless, black-eyed creature of Hell? _Evil?_

"And you're a hunter. I know how this is supposed to work. You think you have to kill me now."

Kill Dean? _Kill _him?

"That's okay, Sammy. I don't blame you. And I promise I won't run, or try to stop you. My death will finish this once and for all."

Dean's death? This was never supposed to end with Dean dying. That was why Sam had taken on the demon trials instead letting his brother sacrifice himself to the cause. He had already watched Dean die too many times to count; he couldn't do it again.

But when they fought Sam had told Dean to go, and he hadn't stopped him. He wasn't there to stop Dean from taking the Mark from Cain.

When he had woken up to an empty bunker a few days ago, Sam had not chased after Dean. He had left him to fight Abbadon and the demon hoard alone.

He let Dean do what he had to, and he had done nothing to save him.

Turns out he was true to his word after all.

"Dean…"

"You will have to convince Cas to give back the First Blade. He wouldn't let me commit suicide, but I am sure you can convince him that this is for the greater good."

Dean wanted to commit _suicide_? He wanted to die? And an _angel_ had to stop him because Sam _wasn't there_?

Again. Sam had done it _again_. After his confessional, he had let Dean down _again_.

And now Dean expected Sam to kill him.

"No," Sam growled.

"What?"

"Let me out of this chair, Dean. Right the hell now."

"Okay, okay, don't get so excited," Dean muttered, coming over to snap the ropes around Sam's arms and legs with his bare hands. "I know you're eager to be rid of me but you don't have to act like Christmas has come early."

"You _idiot_," Sam seethed.

"I know. This'll teach me to read the fine print."

"No, I mean, you are a _complete idiot._ You bust in here, kill Gadreel-" as the last binding snapped Sam surged out of his chair- "_save my life-"_ grabbed Dean in a fierce hug- "-and then you are stupid enough to believe I want to gank you?" He gripped Dean's shoulders and pushed him away slightly to look him in the eyes. "Of course I am not going to kill you, Dean! I don't care what the Mark did to you or what you think you are now. I _know_ what you are.

"You're my brother."

ooOOoo

A/N: Sorry this chapter took so long guys, I have so many assignments to do for uni it is actually crazy. Apologies also for the absence of Cas. But I hope you still enjoyed it! I'm thinking one more chapter to follow…


	5. Chapter 5: Sunset

**Sunset**

It had been a weird week, even by Dean Winchester's standards.

Life as he knew it was over, his world had fallen apart, everything he knew had been turned on its head and Dean himself had been radically altered forever.

Yet somehow, against all odds, he was...okay. Better than okay. _Happy_.

It made no sense. The Mark of Cain had been a road to self-destruction, and it _had_ destroyed him. But at the same time, it had made him new. Not even a _good _new – he was a friggin' demon now, for crying out loud; his humanity had been stripped from him and his mortality with it. Technically, he was a monster. So how exactly was it possible that he was coping with all of this? Not just coping, and not just accepting it as his lot in life, either, but actually coming to terms with it and…embracing it?

An outsider would have to conclude that he was royally screwed in the head. Surely there could be no other explanation.

But Dean had one. Actually, he had two.

One of them currently had his arm slung around Dean's shoulders, leaning on him for support as he struggled to find his sea legs again after having been bound tightly to a chair for three days straight. Despite his height and muscular build, Dean would never think of Sam as heavy – he was Dean's brother, after all – but it was strange how light he felt now that Dean had the supernatural strength of a demon. That alone should have freaked him out, but it felt _good_ to know that he really could carry his brother, just like he always promised he would. Better yet was the fact that Sam was _letting him_ offer his support instead of pushing him away.

A part of Dean still couldn't quite believe it. He was a _demon,_ and by all rights Sam should have been getting busy with the salt, holy water and demon-killing weaponry by now. Hell, even before his freaky metamorphosis, he had given Sam more than one reason to want him dead. Maybe Sam had not quite been driven to the point of outright murder, but he had seemed more than willing to let Dean die if the opportunity presented itself. As much as it had hurt to hear Sam say that he wouldn't save him, Dean had known he deserved it, just like he knew he deserved to be ganked as the Hell-spawn he was.

But even though he had the perfect excuse, Sam wouldn't kill him. Sam didn't _want_ to kill him.

Sam didn't think he was a monster.

Sam had _taken him back_. After everything he had done, after all the crap he had put Sam through, after Sam had said they shouldn't be family, Sam had called him _brother_ again.

_Brother. _Not monster. Not demon. Not freak. _Brother_.

If Sam could see him that way, Dean could too.

It made no sense whatsoever, but he felt more like the real Dean Winchester now than he had in months. Because Dean Winchester was not defined by his humanity, nor by his role as a hunter of the evil things that went bump in the night. He was no more, or less, than Sam Winchester's older brother. Take that away, he was no one. But give him back his Sammy, and Dean was himself again, demonic transformation notwithstanding.

Sam accepted him. So Dean accepted himself. It was as simple as that.

Of course, everything that came along with being a demon still should have scared the crap out of him. The black eyes, the bloodlust he could still feel coursing through his veins, the inhuman strength, the lightning-fast reflexes, and the way killing came as naturally to him as breathing used to, not to mention _immortality_… His freak-out should have lasted for weeks, or months, or possibly even forever.

But Dean had an explanation for that as well, and he was waiting outside the warehouse.

As soon as the brothers made it past the angel-warding, Castiel was hurrying towards them, apparently having a little freak-out of his own.

"Dean! What took you so long? Is Gadreel dead? What happened? Are you okay?"

Dean couldn't help it; he smiled a little. "Easy there, tiger. Everything's fine."

Castiel narrowed his eyes. "Do not patronise me, Dean. The only reason I agreed to let you go after Sam was because I thought I would be there every step of the way, and then you come up with this half-baked plan to weaken Gadreel and take me out of the fight in the process, leaving you alone against the thing that corrupted the world, and I had no way of knowing what killing him would do to you, and you took so long I feared the Mark was dragging you back and I _couldn't get to you_ and-" he noticed the bloodied tear in Dean's shirt "-and you have been STABBED, Dean! Don't tell me everything is fine!"

The angel was yelling at him with righteous fury and it made Dean feel all warm and fuzzy inside. It was nice to know that Cas cared.

"An angel sword couldn't actually kill Dean," Sam pointed out.

"That's not the-" Cas froze, his eyes swivelling to stare at Sam. "What did you say?"

"Well, the First Blade is the only thing that can kill him now, right?"

Castiel's response was immediate and entirely unexpected; he snatched Dean from his brother and threw himself between them, standing protectively in front of Dean and facing off against Sam as though he was an enemy. "I won't let you hurt him," Cas growled.

The brothers spoke simultaneously. "What?"

"I don't care if he is a demon. I will not allow you to hunt him."

"I wasn't going to-"

"And I will not let you talk him into trying to kill himself again either!"

"I wouldn't-" Sam's attention suddenly snapped to Dean. "You tried to _kill yourself?"_

Dean shrank behind his angel bodyguard. "Uh, I thought it was the right thing to do. Ganking the final demon and all that."

Sam took a menacing step forward. "Dean-" Castiel bristled, but Sam ignored him, too preoccupied with yelling at his brother, "-if you _ever_ try to pull that kind of stunt again, so help me I will lock you in a room with nothing but a T.V and a crappy chick-flick playing on repeat for the rest of eternity!"

Dean swallowed nervously and backed away a little.

Cas blinked. "You're… mad at him for harming himself?"

"Damn straight I'm mad at him! You think I want my brother to die?"

"Well don't you?"

"Of course not! I love the stupid son of a bitch!"

"As do I."

"Good. We're on the same page, then. No letting Dean do anything stupid. We're not going to take any more of this self-sacrificial, self-loathing death-wish crap. We're going to keep him alive and happy whether he likes it or not."

"Agreed."

"Um, guys?" Dean piped up. "I'm right here."

"And you're not going anywhere," Sam said firmly. "Alright?"

Dean had to roll his eyes, or else the unreserved grin he felt bubbling up within him might make an appearance. "Okay, okay."

"You promise that you will take care of yourself?" Castiel asked, turning to pin him with a look that said _I have tried too hard to keep you safe to lose you now _and_ I need you to be okay _and_ Don't you dare leave me._

If not for Cas, Dean would still be lost out there on the Killing Field. If not for Cas, he never would have been able to drop the First Blade. If not for Cas, he would have kept trying to kill himself until he tore his body apart. If not for Cas, the prospect of eternal life would have devastated him. If not for Cas, he would never have believed he could be okay.

_With_ Cas, he knew he would never be alone.

"Yeah. I promise."

A faint smile curved Castiel's lips, and he gave Dean a small nod.

"So Gadreel is dead and the demons are gone," Sam summarised, rescuing them all from what could have easily become a chick-flick moment. "That leaves Metatron."

"Well, with the powers of a human, an angel and a demon against him, Metatron doesn't stand a chance," Dean said.

"Once Metatron is dealt with, the angels will be able to return to Heaven. Earth will be left in peace."

"Huh." Peace. After a lifetime of hunting, it was hard to imagine.

"I suppose Heaven will need putting in order, Cas," Sam said. "And Dean, Hell could probably do with a make-over if souls are going to keep heading down there. Of course, there will still be small-fry monsters roaming the Earth, so I could work on training up a few hunters… But that could be it for us. The end."

"And then what?" Cas asked.

"I don't know. Travel? Finally see the world we have saved a dozen times over? Build a new family business? Go to college? Settle down?"

"Doesn't matter what we do," Dean said. "What matters is that we're together."

For the first time ever they had a future, and they had their freedom. It was all they had ever wanted, and it was there on the horizon, waiting for them. The three unlikely heroes could ride off into the sunset.

Dean grinned, clapping both his brother and his angel on the back. "We can do anything we want."

ooOOoo

The End

_A/N: Well there you have it, folks! The one-shot that became a five chapter story is now complete thanks to the encouragement and support of my awesome readers. Special thanks to jojospn, LilyBolt, The Mysterious Shadow, Anna and TMK13 for reviewing throughout the story – you guys kept me going! I hope you all enjoyed taking this journey with me. Any and all feedback is greatly received. _

_And hey, here's hoping Supernatural will give us a similarly happy ending _


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